Fuze apparatus

ABSTRACT

A centrifugally displaced fluid barrier for a spin-operated fuze arming delay. Safing and delay arming is provided by a relatively high density fluid positioned along the spin axis of a munition to block the output of a detonator along the spin axis. The fluid completely fills a chamber with the exception of a relatively small volume air bubble. Under sustained spin environment, the air bubble is displaced by centrifugal forces within the fluid into a position along the axis of the munition, allowing the detonator output to pass through the air chamber. Various configurations of the chamber to provide arming delay are contemplated.

United States atent Carlson et al.

[ Feb. 8, 1972 both of Minneapolis, Minn.

[73] Assignee: Honeywell Inc., Minneapolis, Minn.

[22] Filed: June 20, 1969 [21] Appl. No.: 835,186

FOREIGN PATENTS OR APPLICATIONS 17,795 1905 Great Britain l02/80 PrimaryExaminer-Samuel W. Engle Attorney-Charles J. Ungemach, Ronald T. Reilingand Albin Medved [57] ABSTRACT A centrifugally displaced fluid barrierfor a spin-operated fuze arming delay. Safing and delay arming isprovided by a relatively high density fluid positioned along the spinaxis of a munition to block the output of a detonator along the spinaxis. The fluid completely fills a chamber with the exception of arelatively small volume air bubble. Under sustained spin environment,the air bubble is displaced by centrifugal forces within the fluid intoa position along the axis of the munition, allowing the detonator outputto pass through the air chamber. Various configurations of the chamberto provide arming delay are contemplated.

3 Claims, 2 Drawing Figures Pmmanrw 8H7? 3.640.225

INVENTORS DONOVAN R. CARLSON WILLIAM O. MARUSKA ATTORNEY ruzr: APPARATUSBACKGROUND OF THE INVENTION I. Field of the Invention The presentinvention pertains to percussive fuzes having safety means rendering thefume inactive for handling purposes and fuzes which are centrifugallyarmed in response to rotation of the projectile.

2. Description of the Prior Art Centrifugal arming is well known in theprior art. Most centrifugal arming arrangements, however, comprisemechanical locks and weights. Fluid has been utilized in some cases forthe purpose of delaying the operation of the fuze.

U.S. Pat. No. 3,425,354, issued Feb. 4, 1969 and assigned to theassignee of the present invention, discloses a centrifugally armed fuzewherein fluid is used as a positive force in the arming sequence. Adetonator positioned within a chamber has a normal position toward theperiphery of the chamber. Upon spin, a buoyant slider member isdisplaced by the centrifugal force of the fluid to the center of thechamber in line with the spin axis of the munition where it is inposition to be actuated by a firing pin and in turn initiate apyrotechnic chain.

It is an object of the present invention to provide a simplespin-operated arming mechanism utilizing no moving parts.

SUMMARY OF THE INVENTION The present invention provides a centrifugallyactuated fluid barrier for spin-actuated, delay arming fuzes. The fluidbarrier is positioned across the spin axis to block a detonator outputalong the spin axis. The barrier is made up of a preferably circularcross-sectional chamber positioned perpendicular to the spin axis. Thechamber is filled with a relatively high-density fluid containing abubble. The chamber design is such that the bubble stays around theperiphery of the chamber and will not locate itself along the spin axisexcept under sustained spin.

Under sustained spin, centrifugal force tends to push the fluid radiallyoutward from the spin axis which centers the bubble along the spin axis.The detonator, having anoutput along the spin axis, can then initiate alead cup or other explosive through the gap. Delay is achieved byselecting a viscous fluid through which the bubble will move at acontrolled rate commensurate with chamber diameter, spin rate, and delayrequirements. The delay may therefore be adapted to suit almost any spinto arm fuze application.

Premature initiation of the detonator will cause the detonator output tobe blocked by the fluid barrier, thus protecting a lead explosive. Thecentral portion of the chamber located along the spin axis is restrictedin dimensions to prevent the bubble from entering this regionaccidentally during handling.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of atypical embodiment of the invention.

FIG. 2 is a cross-sectional view of the embodiment of FIG. 1 incombination with a percussive fuze.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. I, a radiallysymmetrical chamber generally designated 1 is filled with a high-densityfluid 2. The chamber 1 is completely filled with the exception of asmall void 3 taking the form of a bubble. The central portion of thechamber is separated from the periphery by a restriction 4. The bubble 3is therefore prevented from crossing through the center section due tothis restriction. Upon spinning this barrier about the axis of symmetry,however, the centrifugal forces in the fluid displace the bubble 3toward the center, causing it to deform from its natural spherical shapeand pass through the restriction 4. In the absence of sustained spin,the bubble 3 will never enter the central region of the chamber 1.

Referring to FIG. 2, the chamber 1 is shown positioned in a munitioncomprising a nose 6 crimped onto a base portion 7 and having a plasticprobe 8 inserted in the forward portion. A firing pin is located in acavity directly aft of the probe 8. The firing pin 9 is separated from adetonator 10, also located along the axis of the munition, by a collar11. The detonator 10 is positioned to fire toward the rear of theprojectile along the axis into a lead cup 12. Between the detonator 10and the lead cup 12 is a fluid barrier mechanism as represented inFIG. 1. The port between the detonator output and the lead cup 12 isblocked by the fluid contained within the chamber 1.

During launch of the embodiment shown in FIG. 2, all components arestationary. After the specified delay time in a spin environment, theair (or other appropriate gas) bubble is forced through the restrictionand aligns with the explosive train along the munition axis between thedetonator l0 and the lead cup 12. Upon impact, the plastic probe 8 isextruded through the hole in the ogive, shearing off the shoulder 11 onthe firing pin 9. The firing pin is thus driven into the stab-initiatingdetonator 10. The detonator output initiates the lead cup through theair bubble and the frangible walls of the chamber.

The many variations possible on the configuration of the chamber will berealized by those skilled in the art. The considerations for the designof the chamber are that the bubble never pass through the center of thechamber under normal handling and that the barrier be of sufficientthickness to block the detonator output should it be initiated beforearming is achieved. The thickness of thechamber is adjusted to requiredeformation of the bubble from its normal spherical shape in an armed"position. Due to the tendency of the bubble to remain spherical, acontinuous force from all sides must be maintained to hold the bubble inits armed position.

Wherein I claim:

1. A centrifugally displaced fluid barrier for positioning on a spinaxis of a spin munition, and between a lead explosive and a detonatorpositioned to initiate said lead explosive along the spin axis,comprising:

a hermetically sealed housing defining a chamber, said chamber beingcompletely filled with a relatively highdensity fluid except for abuoyant bubble contained within and defined by said fluid, said housinghaving a restriction therein which prevents said bubble from beingpositioned along said spin axis unless said munition experiencessustained spin.

2. A fluid barrier safing and arming mechanism for separating an axiallypositioned detonator and lead cup in a spin operated fuze, comprising ahermetically sealed housing defining a chamber, said chamber beingcompletely filled with a viscous fluid except for an air bubblecontained within and defined by said fluid, said housing having aannular restricted thickness portion requiring deformation of said airbubble to occupy a position along the axis of said fuze, whereby saidair bubble remains away from the axis of the fuze in all orientationsexcept under a sustained spin environment thereby allowing the detonatorto fire through the air bubble to initiate the lead cup.

3. A centrifugally displaced fluid barrier for positioning on a spinaxis of a spin munition, and between a lead explosive and a detonatorpositioned to initiate said lead explosive along the spin axis,comprising:

a radially symmetrical hermetically sealed housing defining a firstchamber and a second chamber, said chambers being positioned coaxiallywith said spin axis between said detonator and said lead explosive, saidsecond chamber being further from said spin axis than said first chamberand communicating with said first, chamber through a restricted portion,said chambers being filled with a relatively high-density fluid free toflow therebetween, said fluid containing and defining a bubble, saidbubble being normally within said second chamber and unable to passthrough said restricted portion into said first chamber until saidmunition fuze experiences sustained spin whereupon said bubble becomespositioned along said spin axis.

1. A centrifugally displaced fluid barrier for positioning on a spinaxis of a spin munition, and between a lead explosive and a detonatorpositioned to initiate said lead explosive along the spin axis,comprising: a hermetically sealed housing defining a chamber, saidchamber being completely filled with a relatively high-density fluidexcept for a buoyant bubble contained within and defined by said fluid,said housing having a restriction therein which prevents said bubblefrom being positioned along said spin axis unless said munitionexperiences sustained spin.
 2. A fluid barrier safing and armingmechanism for separating an axially positioned detonator and lead cup ina spin operated fuze, comprising a hermetically sealed housing defininga chamber, said chamber being completely filled with a viscous fluidexcept for an air bubble contained within and defined by said fluid,said housing having a annular restricted thickness portion requiringdeformation of said air bubble to occUpy a position along the axis ofsaid fuze, whereby said air bubble remains away from the axis of thefuze in all orientations except under a sustained spin environmentthereby allowing the detonator to fire through the air bubble toinitiate the lead cup.
 3. A centrifugally displaced fluid barrier forpositioning on a spin axis of a spin munition, and between a leadexplosive and a detonator positioned to initiate said lead explosivealong the spin axis, comprising: a radially symmetrical hermeticallysealed housing defining a first chamber and a second chamber, saidchambers being positioned coaxially with said spin axis between saiddetonator and said lead explosive, said second chamber being furtherfrom said spin axis than said first chamber and communicating with saidfirst chamber through a restricted portion, said chambers being filledwith a relatively high-density fluid free to flow therebetween, saidfluid containing and defining a bubble, said bubble being normallywithin said second chamber and unable to pass through said restrictedportion into said first chamber until said munition fuze experiencessustained spin whereupon said bubble becomes positioned along said spinaxis.